Annunciator assembly



Nov. 8, 1960 w. c. ARRAsMrrH 2,959,774'

ANNUNCIATOR ASSEMBLY 2 sh t -s t Filed July '7, 1959 ee s hee -2 2,959,774 Patented Nov, 8,1960

ANN UNCIATOR ASSEMBLY William C. Arrasmith, Los Angeles, Calif., assignor to Radar Relay, Inc., Santa Monica, Calif., a corporation of California Filed July 7, 1959, Ser. No. 825,461

13 Claims. (Cl. 340-324) The present invention relates to an improved assembly for use in electrically operated alarm systems of the annunciator type. The invention is more particularly concerned with an improved unit for use With a plurality of similar units on a central panel to provide visual indications of the occurrence of remote, identified hazardous conditions.

Annunciator warning systems are in general well known. An eilicient system of this type is disclosed and claimed, for example, in copending application Serial No. 505,305 which was led March 2, 1955 in the name of the present inventor, and which has been assigned to the present assignee. This application issued on May 19, 1959 as Patent No. 2,887,677.

Annunciator warning systems of the type disclosed in the copending application, for example, usually include a plurality of electrically energized lamps. These lamps are mounted in suitable housings on a central control panel, and appropriate circuitry is provided for respectively connecting the lamps to corresponding sensing elements. The sensing elements are located at different points of the monitored area, and each sensing element may include a pair of normally open electrical contacts. These contacts are constructed to close by the sensing unit whenever the condition monitored by that particular sensing element actually occurs.

It is usual to group the electrically energized lamps in shunt-connected pairs, so that if one lamp burns out, the second will still glow if the contacts of the corresponding sensing element should close. It is also known to mount each pair of lamps in a separate elongated translucent annunciator member by means of appropriate sockets. Each of these annunciator members may have a at panel-like front face which carries inscriptions identifying the corresponding monitored condition. These inscriptions may read, for example, fuel low, generator off, hatch open, etc.

When the electrical contacts controlled by one of the above mentioned sensing elements closes, an energizing circuit is completed to its pair of lamps, and the translucent annunciator member associated with these lamps is illuminated. This illumination of the iront panel of the Ser. No. 617,618 are designed and constructed so that they may conveniently be mounted on top of one another and held in an assembled stacked relationship, The stacked capsules are then mounted on the rear of a control panel, and their respective translucent annunciator mem-bers are plugged into the different capsules through openings in the panel and from the front of the panel.

The construction of the annunciator members and associated capsules of the copending application Ser. No. 617,618 is such that the individual capsules may be easily removed fro-m the stack and replaced should the occasion arise. Also, the individual translucent annunciator mem'-A bers of the copending application Ser. No. 617,618, and the lamps contained in these members, are removable from the front of the panel merely by an unplugging operation. This permits the velectrically energized lamps in the different annunciator members to be replaced as' translucent annunciator member causes its inscriptions to 5 become visible.

Copending application Serial No. 617,618 tiled October 22, 1956 in the name of the present inventor and assigned to the present assignee discloses and claims improved apparatus of the type described briefly in the preceding paragraphs. This latter application issued on April 26, 1960 as Patent No. 2,934,752.

In the apparatus described in the copending application Serial No. 618,617, the control circuits and control elements associated with each pair of electrically energized lamps are positioned in a small rectangular shaped capsule, and the elongated translucent annunciator member which is to be illuminated by the lamps is constructed to be plugged into the front edge of the capsule.

` The capsules described in the copending application they are burned out.

The present invention is concerned in one of its aspects with an annunciator assembly of the type discussed in the preceding paragraphs, and described and claimed in the copending application Ser. No. 617,618. An important feature of the present invention, however, is that the individual translucent annunciator members can be mounted flush with the front surface of the supporting panel. This is a distinct advantage over the prior art arrangements in which the individual annunciator members usually were mounted to project outwardly from the front face of the control panel. This was necessary with the prior art units to permit the individual annunciator members to be removed for the replacement of burned out lamps.

In accordance with the concepts and structural features of the present invention, any particular individual translucent 4annunciator member can be removed from its yassociated capsule, or housing, merely by depressing-'the particular annunciator member inwardly with respect Vtothe plane of the front face of the supporting panel, and they by releasing the annunciator member. This causes an improved latching mechanism which is incorporated into the assembly of the invention to operate and displace Athe particular annunciator member outwardly from the plane of the supporting panel and to a position in which it can be easily removed.

The assembly of the present invention, yas described above, is not only advantageous in the convenience with which the individual translucent annunciator members can be removed to replace burned out lamps, but it also permits the individual annunciator members to be mounted Hush with the front surface of the control panel. This is most advantageous, for example, in the cockpit of an aircraft where it is most desirable to have a minimum of elements projecting from the plane of their supporting panels.

The annunciator warning assemblyof the invention is also advantageous in that it permits a large number of translucent annunciator members to be supported in a minimum of space on a control panel. Even though the different annunciator members are positioned closely adjacent to one another, each may be conveniently lremoved without interference from the adjacent members, this being achieved merely by depressing the member which is to be removed and then releasing that member. The subsequent release causes the associated latching mechanism, in accordance with the concepts of the invention,- to displace the particular annunciator member to -a position at which it protrudes out from the plane of the control panel and of the other annunciator niembers;.`

The assembly of the invention can be used in conjunc-,Q

tion with the capsule type of units described above. However, the invention, as will become evident, finds general utility whenever a plurality of individual strip or bar members, for example, are to be mounted on a supporting panel; and when it Ais desired that such members be conveniently and individually removable, and that they be normally disposed ush with the front face of the supporting panel.

The above and other aspects and -advantages of the invention will become apparent from the following description, when taken `in conjunction with the accompanying drawings, which:

iFigure 1 is a rear perspective view of a plurality of capsules assembled in a ,stacked condition and mounted un .the rear -fesc of a control panel, each of the illustrated capsules containing circuitry and control elements for ically energized lamps which are controllable to te annunciator members mounted on tbe dinereut ,Capsules in accordance with the concepts of the preseut invention;

Figure 2 is a front view of a panel of Figure l and illustrates the f ront faces of the different annunciator members and typical inscriptions that may be carried on those faces;

Figure 3 is a top view of one of the capsules of Figure 1 with the various control elements and circuitry included in that capsule being removed for purposes of clarity, and this view illustrating the manner in which a translucent annunciator member is releasably supported on the front edge of the capsule in a manner to permit it to be flush with the front surface of the supporting panel;

Figures 4, 5, 6 and 7 are fragmentary schematic illustrations of a latching mechanism constructed in accordance the invention and which serves to releasably support an annunciator member on its associated capsule housing, `these views illustrating how the annunciator member may be disengaged by depressing it inwardly toward the housingV and by subsequently releasing it;

vFigure 8 is a fragmentary view, partly in section, of a plug member which is mounted on each translucent annunciator member, and which has a cylindrical member slidably mounted on it, for reasons to be described;

iFigure 9 is a circuit diagram of a suitable control system for the annunciator units of the present invention; and

'Figure 10 is a top view of one of the capsules of Figure 1, similar to the view of Figure 3, but incorporating certain modifications in accordance with a second embodiment vof the invention.

A s stated previously, and as described inthe copending application Ser. No. 617,618, the control circuit and elementsA for each pair of electrically energized lamps inthe system may be individually housed in a separate capsule, and the translucent annunciator member to be illuminated by the energizing of the particular pair of lamps is supported on one edge of the capsule in a manner to be described, Such capsules are designated 10 in Fig-` ure. 1i which,` illustrates e. stack. of `similar annunciator capsules;-

'lfhe annunoiator capsules 1 0 are held together in a stacked condition by a plurality of bolts 14 which extend through the entire stack and which have appropriate nuts threaded to their extremities to hold the stack of capsules in an assembled condition. The stacks of capsules are supported on the rear face of a control panel 16 by means f a plurality of screws, such as the screws 18. The individual capsules may be spaced rearwardly from the I car face of the control panel 16 by a plurality of spacer members 20 which `may be inserted between the leading edge of eachof the capsules and the rear face of the panel 16.

t Each of the capsules 10 includes a translucent annunciator member 22 'associated with it. As shown in Figures 1 and 2, the annunciator members 22 may havea general- 1y` elongated .rectangular configuration, and they are received by corresponding openings in the panel 16 and are supported on the front edge of their respective capsules 10 in a manner to be described.

As shown in Figure 2, for example, each of the translucent annunciator members 22 has suitable inscriptions formed on its front face. These inscriptions identify the particular hazardous condition monitored by that particular annunciator` member. Whenever the particular hazardous condition actually occurs, and in a manner to be described, the resulting closure of a pair of sensing element contacts causes a corresponding pair of electrical energized lamps to illuminate the particular one of the annunciator members 22.

As shown, for example, in Figures 1 and 3, the annunciator members 22 are supported by their corresponding capsules 10 in positions such that their front faces are flush with the front face of the supporting panel 16. This, as mentioned above, is convenient in that it not only removes the undesirable condition of having projectlng Velements in a cockpit, for example; but in addition the improved latching mechanism of the invention permits the'diiferent annunciator members 22 to be mounted closely adjacent to one another and yet be removed in a simple manner without interference from adjacent members, as will be explained.

As noted above, each of the capsules 10 contains the circuitry and control elements necessary to control the pair of electrically energized lamps associated with that particular capsule. To this end, each of the capsules has a plurality of terminals designated 28a, 28b, 28e, 28d and 28e mounted on its rear edge, and an additional terminal 32. The terminals 28a of all the capsules in the stack are connected together, as shown in Figure 1, and this applies to the terminals 2811, 28e, 28d and 28e. The respective terminals 32 on the other hand, are connected to the different sensing elements in the area to be monitored.

As illustrated in Figure 3, each capsule 10 includes a pair of electric lamp sockets 24 mounted on its forward edge. 'Ihe sockets 24 may be of any known physical construction and configuration, and they serve to support a corresponding pair of electrically energized lamps 26. The lamps 26 are received in corresponding openings` in the rear face of the associated annunciator member 22, when the same is positioned in the corresponding opening in the control panel 16. It will be observed that the annunciator 22 is normally positioned, as illustrated in Figures 1 and 3, in the opening in the panel 16 so that its front 'surface is flush with the front surface of the panel 16.

A plug member 30 (Figure 3) is mounted on the annunciator 22, and the plug member extends from the rear surface of the annunciator member. The annunciator member 22 is removable from the capsule 10, and when it is moved into place in the opening of the panel 16, the plug member 30 extends through an aperture in the front Wall of .the capsule 10.

AA resilient jack 31 is mounted in the capsule 10 `in axialV alignment with the aperture inthe front wall of the capsule. The plug 30 has a ball-shaped extremity 30a and that extremity is engaged by the resilient jack 3].` when, the plug 30 is inserted into the capsule 10.` The jack 31 includes a pair of spaced arms 33 which areA supported at one end by a screw 35. The arms are resilient and their free ends are shaped to releasably engage the ball-shaped extremity 30a of the plug. The screw 35 supports the arms 33 on a bracket 37, and the bracket is` mounted to .the rear wall of the capsule 10 by a screw V39.

The jack 31 serves toihold the annunciator member 22 in position in the opening of the control `panel 16. When the annunciator member is in that position, the lamps 26 arereceived by the openings in the rear face of the annunciator member, and these lamps illuminate the inscriptions on the front face of the annunciator member 22, when the lamps are energized.

The plug has a cylindrical member 34 slidably mounted on it, as best shown in Figure 8. The cylindrical member 34 has an inner diameter which is slightly greater than the outer diameter of the ball-shaped eX- tremity 30a of the plug 30. This permits the cylindrical member 34 to slide to the end of the block 30 and to a position covering the ball-shaped extremity of the plug, as shown in Figure 8. The rear end of the cylindrical member 34 is turned inwardlyyas shown at 34a, and inwardly turned end of the cylindrical member 34 engages a shoulder 36 on the plug 30 to prevent the cylindrical member from moving oif the end of the plug. A collar 38 is secured to the plug 30 to the rear rof the cylindrical member 34, and this collar serves to push the cylindrical member into the jack 31 so as to disengage the ball-shaped end 30a of the plug 30, when the annunciator member 22 is displaced inwardly toward the capsule 10.

A second collar (Figure 3) is slidably mounted on the plug 30 in front of the collar 38. The collar 40 has a diameter greater than the diameter of the plugreceiving aperture in the front wall of the capsule 10. A coil spring 42 is mounted on the plug 30 between the rear face of the annunciator member 22 and the collar 40, and this spring engages the collar and the annunciator member 22 to bias the annunciator member outwardly from the front wall of the capsule 10.

The manner in which the latehing mechanism of the invention operates when it is desired to release the annunciator member 22 is shown by the fragmentary schematic diagrams of Figures 4-7.

The illustration of Figure 4 shows an annunciator member 22 in its'position as normally engaged by the jack 31 and held in place on its corresponding capsule 10. When it is desired to release the annunciator member, it is depressed inwardly towards the capsule 10 as shown in Figure 5. This causes the collar 38 to move the cylindrical member 34 into the jack 31 and spread the arms 33 of the jack so as to disengage the ball-shaped extremity 30a of the plug from the jack. Then, when the annunciator member 22 is subsequently released, and as shown in Figure 6, the resilient spring 42 biases the member outwardly from the capsule 10 to withdraw the ball-shaped end 30a of the plug 30 down into the cylindrical member 34. The annunciator member 22 is now displaced outwardly from the plane of the front surface of the panel 16 in position to be removed.

i. The cylindrical member 34 may be provided with a peripheral groove 34a (Figure 8) near its forward ex- `tremity, and the arms 33 of the resilient jack 31 engage this groove with a slight retaining pressure when the cylindrical member is moved into the jack.

Now, to remove the plug assembly from the jack 31, and as shown in Figure 7, it is merely necessary to move the displaced annunciator member 22 outwardly and away from its associated capsule. This removal reveals the lamps 26 on the edge of the corresponding capsule 110';l so that they mayl be easily removed and replaced. Then, the annunciator member 22 may again be plugged into its capsule 10 into the plug-jack relationship illustrated in Figure 4.

The terminals 28a, 28h, 28C, 28d and 28e of Figure l are shown in the circuit diagram of Figure 9, and the Vterminal 32 of Figure 1 is also shown in Figure 9. Each of the capsules 10 contains a single relay having an energizing winding and having a pair of armatures 52. and 54. Whenthe winding 50 is-energized, the arma'tu're 52 opens from its upper contact and closes on its inactive llower contact. At the same time, when the winding 50 is energized, the armature 54 opens from its inactive lower contact and closes on its upper contact. )One terminal of the winding 50 is connected to the ,terminal 32, and the other terminal of this winding is f3 connected to the cathode of a diode 56. The anode of vthis diode is connected to the terminal 28e.

The upper contact associated with the relay armature 54 is connected to the common junction of the diode 56 and the winding 50. The armature 54, itself, is connected to the terminal 28b. The armature 52 is connected to the common junction of the winding 50 and the terminal 32. The upper contact associated with this armature is connected to the cathode of a diode 60. The anode of this diode is connected to the terminal 28a.

The two electrically energized lamps 26, referred to in conjunction with Figure 3, are mounted in the described manner, and are connected in parallel, as shown in Figure 9. These shunt connected electrically energized lamps are connected through their sockets 24 (Figure 3) to the common junction of the'winding 50 and the terminal 32 in Figure 9, and to one terminal of a resistor 62. The other terminal of the resistor 62 is connected to the terminal 28b.

A diode 64 has its cathode connected to the common junction of the lamps 38, 40 and the resistor 62, and the anode of this diode is connected to the terminal 28d. A diode 66 has its cathode connected to the terminal 28C and the anode of this diode is connected to the terminal 32. The elements and circuitry described above are similar to those described in the copending application Ser. No. 617,618 referred to above, and they constitute suitable internal connections and components for each of the capsules 10.

The five leads from the respective terminals 28a, 28b, 28C, 28d and 28e of Figure l are designated 74, 68, 76, 72 and 70. The lead 68 is connected, as shown in Figure 9, to the positive terminal of a source 78 of direct voltage, the negative terminal of this source being ground.- ed. The lead 70 is connected to the xed contact of a test switch 80. This switch may be in the form of a single-pole single-throw manually operated push button switch. The armature of the switch is normally biased out of engagement with the Xed contact, and the armature is grounded.

The lead 72 is connected to the fixed contact of a dimmer switch 82. This latter switch may also be in the form of a single-pole single-throw manually operated push button switch. The armature of the switch 82 is connected to the positive terminal of the source 78. The armature of the switch 82 is normally biased into engagement with its Xed contact, and when the movable arm is depressed, the connection from the positive terminal of the source 78 to the lead 72 is broken.

The lead 74 is connected to a terminal 84 of a master warning instrument 86. The terminal 84 is connected to one side of a pair of shunt connected master warning electrically energized lamps 88 and 90. A resistor 92 connects the other side of these shunt connected lamps to a terminal 94 of the unit. A further terminal 96 is connected to the anode of a diode 98, and the anode of this diode is connected to a common junction of the lamps 88, and the resistor 92. The terminal 96 is connected externally to the lead.72. The unit 86 also includes an acknowledge or reset switch 100. The f switch is normally spring biased to an open condition and it is a single-pole single-throw type. The xed contact of the switch is connected to a terminal 102 of the unit 86 which, in turn, is connected to the positive v terminal of the source 78. The armature of the switch 100 is connected to a terminal 104 of the instrument 86, and this terminal is connected externally to the lead 76. The terminal 94 of the instrument is connected externally to the positive terminal of the source 78. v

The terminal 32 is connected to the armature of a switch 106 incorporated in a sensing element in the area to be monitored. This switch is actuated in known manner to close in response to the occurrence of a certain condition. The switch includes a xed contact which is grounded, and the armature of the switch closes' with the fixed contact upon the occurrence of a certain condition as, for example, the rise of pressure or temperature above a selected threshold, a drop in oil pressure, the mechanical shifting of anelernent, etc. Sensing elements, in themselves, are well known in the art. It is believed, therefore, that a detailed description of such an element is not necessary to the understanding of the present description.

Assume now that the hazardous condition monitored by the sensing element No. 1 has occurred, thereby causing the armature vof the switch v106` in that element to close on its grounded xedcontact. The closure of the switch 106 places a ground on'the terminal 32 of the capsule 10. This completes `a circuit from the negative terminal ofthe source .78 through the annunciator lamps 26, through the diode 64, `and through the switch 82 to the positive terminal of the `source 78. The annunciator lamps 26, therefore, glow brightly and illuminate the inscriptions on their associated annunciator member 22.

The closure of the switch 106 of the sensing yelement No. 1 also completes a circuit from the negative terminal of the source 78 through the terminal 32, through the armature 52 of the relay and its upper contact, down through the diode 60, through the master warning lamps 88 and 90 through the diode 98, and through the dimmer switch 82 to the positive terminal of the source 78. The master warning lamps 88 and 90, therefore, also glow brightly.

It should be pointed out that the master warning instrument is usually located in such a position that it may readily catch the eye of the operator to inform him of the fact that something is wrong. The operator then turns to the annunciator members 22 to determine the locality of the fault or hazardous condition. When Ythe operators attention has been attracted by the glowing lamps in the master warning instrument, the instrument has served its purpose. Now, the master warning lamps can be de-energized and placed in readiness to indicate another monitored hazardous condition that might arise. This de-energizing of the master warning lamps is accomplished by closing the reset switch 100.

When the reset switch 100 is closed, the lead 76 connects the terminal 28C of the capsule to the positive terminal of the source 78. This causes the relay winding 50 to be energized to move the arm 54 to its upper contact. The arm 54 now establishes a circuit which holds the winding 50 energized so long as the fault at the No. l sensing element causes the switch 106 to remain closed. At the same time, the energizing of the relay winding 50` causes the arm 52 to move from its upper contact to break the connection of the lamps 88 and 90 in the master warning instrument. The master warning lamps, therefore, are de-energized. However, the annunciator lamps 26 remain energized and their corresponding annunciator member 22 remains illuminated as long as the fault continues.

The dimmer switch 82 serves .as a means for dimming the annunciator lamps 26 .and the master warning lamps 88 and 90 when so desired. When the dimmer switch 82 is depressed, the circuit through the diode 64 from the annunciator lamps 26 is broken, and -an auxiliary circuit through the resistor 62 and through the terminal 28b to the positive terminal of the source 78 is established. rIhe annunciator lamps, therefore, continue to glow but with reduced luminance because the resistor 62 has `effectively been placed in their energizing circuit. Likewise, the actuation of the `dimmer switch 82 breaks the circuit from the master warning lamps 85 ,and 90 through the diode 98, and causes these lamps to be energized through the terminal 94 and through the resistor 92. The master warning lamps, therefore, also continue to glow but also with reduced brilliance.

The test switch 80 is effectively connected through the diode 66 in shunt across the sensing elements. When this test switch is actuated, it stimulates the closure of all the sensing elements so that appropriate tests can "ce made to assure that the system is in proper working order.

In the embodiment of Figure l0, the elongated trans'- 'lucent annunciator member 22 is also supported on its capsule 10 in a position such that its front face is normally ush with the front of the panel 16. Inthe latter embodiment the electrically energized lamps 26 are sup# ported in the annunciator member itself in rmpective plugs 27. The plugs in turn are supported removably in the sockets 24 on the front edgeof the capsule 10,

The above Adescribed `arrangement is such that when the member 22 is depressed and released to cause it to spring out from the panel 16, the plugs 27 are drawn out of the sockets 24 a suflicient distance to de-energize the lamp 26. This `is advantageous in that it permits the pilot to de-energize any particular annunciator member after he has been made aware lof the fault. This obviates the annoyance of `the presence of a glowing annunciator panel after the fault has been appreciated, especially if the `fault is one that need not be corrected immediately.

In the embodiment of Figure 10, the end of the plug 30 has a notch 131 formed in it; and this notch is positively engaged by a pair of resilient members 133, 135. The resilient members form the jack in the latter embodiment, and they are fastened `to the front edge of the capsule by suitable means, such as by a pair of pins 137, 139. The plug 30 is released from the jack by the cylindrical member 34 in exactly the same manner as described above for the previous embodiment.

It will be remembered that, as stated above, each annunciator member 22 has a particular inscription on its face corresponding to the fault it is monitoring. It is important, therefore, that an annunciator member should never be plugged into the wrong capsule, for then a false designation would be given should the fault monitored by that particular capsule arise.

To prevent an annunciator member 22 from being plugged into the wrong capsule, the embodiment of Figure l0 provides means for caging the annunciators in their associated capsules. This means permits the annunciator member to be withdrawn out .from the front edge of the capsule a suicient distance to replace the lamp 26, but does not permit the annunciator member to be completely removed from its capsule.

The caging means referred to in the preceding paragraph takes the form in the embodiment of Figure 10 of a pair of strip-like slide members 41 and 43. These slide members are molded into the annunciator member 22 and they extend through the front edge of the capsule 10 and into its interior. The lrear extremities of the slide members 41 and 43 are bent over to engage corresponding shoulders in the side walls of the capsule 10 when the annunciator member is drawn out from the panel 16 toits permissible limit.

The invention provides, therefore, an improved annunciator assembly in which the different annunciator members may be held ush with the control panel. The improved assembly of the invention `also provides, by means of an improved latching mechanism, for the con,- venient release of individual ones of the annunciator members. This release is carried out, as described above, by merely depressing the selected annunciatormember and then releasing it. This causes the selected 'member to be displaced outwardly from the plane of the control panel for its convenient removal.

I claim:

r1. An assembly for use in an electrical system `including: a housing having an aperture therein, a movable member, an elongated plug member mounted on the movable member and projecting from the movable member to be inserted in the aperture in the housing, a resilient jack mounted in the housing in alignment with the aperture therein `to engage the plug and therebyhold '9 the movable member on the housing, and means for releasing the elongated plug member from the resilient jack when the movable member is moved in the direction of the housing.

2. An indicating assembly for use in an electrical system including: a housing having an aperture therein, an annunciator member, an elongated plug member mounted on the annunciator member and projecting from the annunciator member to be inserted in the aperture in the housing, a resilient jack mounted in the housing in alignment with the aperture therein to engage the extremity of the plug and thereby hold the annunciator member in the housing, a cylindrical member slidably supported on the plug adjacent the extremity thereof, and means coupled to the plug for forcing the cylindrical member into the jack to disengage the extremity of the plug from the jack when the annunciator member is moved in the direction of the housing.

` 3. An indicating assembly for use in an electrical system including: a housing having an aperture therein, an annunciator member, an elongated plug member having a peripheral groove adjacent the extremity thereof and mounted on the annunciator member and projecting from the annunciator member to be inserted in the aperture in the housing, a resilient jack mounted in the housing in alignment with the aperture therein to engage the groove in the extremity of the plug and thereby hold the annunciator member on the housing, a cylindrical member slidably supported on the plug adjacent the extremity thereof, -a collar secured to the plug to the rear of the cylindrical member for forcing the cylindrical member into the jack to disengage the groove at the extremity of the plug from the jack when the annunciator member is moved in the direction of the housing, and resilient means for retracting the plug from the jack when the groove at the extremity thereof is so disengaged from the jack by the cylindrical member.

4. An indicating assembly for use in an electrical Warning system including: a housing having an aperture therein, an annunciator member, an elongated plug member having a ball-shaped extremity and mounted on the annunciator member and projecting from the annunciator member to be inserted in the aperture in the housing, a resilient jack mounted in the housing in alignment with the aperture therein to engage the ball-shaped extremity of the plug and thereby hold the annunciator member on the housing, a cylindrical member slidably supported on the plug adjacent the ball-shaped extremity thereof and movable toy a position covering the ball-shaped extremity, a collar secured to the plug to the rear of the cylindrical member for forcing the cylindrical member into the jack to disengage the ball-shaped extremity of the plug from the jack when the annunciator member is moved in the direction of the housing, a second collar slidably mounted on the plug and having a diameter greater than the diameter of the aperture in the housing, and a resilient member mounted on the plug between the annunciator member and the second collar to bias the second collar against the housing so as to retract the plug from the jack when the ball-shaped extremity thereof is so disengaged from the jack by the cylindrical member.

5. An indicating assembly for use in an electrical warning system including: a housing including a front wall having an `aperture therein, an annunciator member, socket means for supporting at least one electric lamp in position to illuminate the annunciator member when the annunciator member is mounted on the housing, and means for mounting the annunicator member on the housing and including latching means for releasing the annunciator member when the same is moved in the direction of the housing.

6. An indicating assembly for use in an electrical warning system including: a housing including a front wall having `an aperture therein, `an elongated `annunciator member of generally rectangular configuration and composed of'translucent material, socket means mounted on the front wall of the housing for supporting at least one electric lamp in position to illuminate the annunciator member when the annunciator member is mounted on the housing, an elongated plug member mounted on the anjnunciator member and projecting from the rear face of the annunciator member to be inserted in the aper ture in thev front wall of the housing, a resilient jack mounted in the housing in alignment with the aperture therein to engage the plug and thereby releasably mount the annunciator member on the housing, and means for releasing the elongated plug member from the resilient jack when the annunciator member is moved in the direction of the housing. j

7. An assembly to be mounted on a supporting panel including: a housing to be mounted on the rear face of the panel adjacent an opening in the panel, a movable member having a configuration to be received by the opening in the panel, means for mounting the movable member on the housing in position in the opening in the panel, and latching means included in the mounting means for releasing the annunciator member when the same is moved into the opening in the panel in the direction of the housing.

8. An indicating assembly for use in an electrical warning system and to be mounted on a supporting panel, said assembly including: a housing to be mounted on the rear face of the panel with a front edge thereof facing an opening in the panel, a translucent annunciator member having a conguration to be received by the opening in the panel and having a front'face with inscriptions formed thereon, socket means for supporting at least one electric lamp in position to illuminate the annunciatormember when the annunciator member is positioned in the opening in the panel, means for mounting the annunciator member on the housing in position in the opening in the panel with the front face of the annunciator member flush with the front face of the panel, and latching means included in the mounting means for releasing the annunciator member when the same is moved into the opening in the panel in the direction of the housing.

9. An indicating assembly for use in an electrical warning system and to be mounted on a supporting panel, said assembly including: a housing to be mounted on the rear face of the panel with .a front edge thereof facing the rear face of the panel, electric socket means for at least one electrically energized lamp supported on the front edge of the housing adjacent an opening in the panel, a translucent annunciator member having a conguration Vto be received in the opening in the panel and having inscriptions formed on a front face thereof and further having an opening therein to receive the electrically energized lamp, an elongated plug member mounted on the translucent annunciator member having a ball-shaped extremity and projecting from the rear face of the translucent member to be inserted in an aperture in the front edge of the housing, a resilient jack mounted in the housing in alignment With the opening in the front edge thereof to engage the ball-shaped extremity of the plug and thereby hold the translucent member in place in the opening of the panel with the front edge of the translucent member flush with the front face of the panel, a cylin drical member slidably mounted on the plug adjacent the ball-shaped extremity thereof, a collar mounted on the plug to the rear of the cylindrical member to force the cylindrical member into the jack so as to disengage the extremity of the plug from the jack when the translucent member is depressed inwardly into the plane of the panel, and resilient means mounted on the plug for retracting the translucent annunciator member out of the plane of the front face of the panel when the ball-shaped extremity of the plug is disengaged from the jack by the cylindrical member.

l0. An indicating assembly for use in an electrical warning system including: a housing having an aperture therein, an annunciator member, 'an elongated plug mem; ber mounted on the annunciator `member and projecting from the annunciator member to be inserted in the aper-` ture in the housing, a resilient jack mounted in the housing in alignment with the aperture therein to engage the plug and thereby hold the annunciator member on the housing, means for releasing the elongated plug member from the resilient jack when the annunciator member is moved `in the direction of thehousing, and cag'ing means extending from the annunciator member into the housing to prevent Ithe removal of the annunciator member from the housing.

11. The combination defined in claim in which the caging means includes at least onestrip-,like slide :niember axed to the annunciator member and `extending from the rear face thereof into the housing in sliding relationship with the housing, and "said slide member `including means for preventing the complete withdrawal thereof from the housing.

112. An indicating assembly `ior use in an yelectrical warning system including: a housing having zanfaperture in the front edge thereof, an annunciator member, an elongated plug member `having a peripheral groove at the extremity thereof mounted on the annunciator member and projecting from the annunciator member to be inserted in the aperture in the housing, a resilient jack mounted in the housing at the front edge of the housing adjacent the aperture and having at `least one resilient member positioned to engage the peripheral groove in the hplug member when the plug member is inserted into the aperture and thereby hold the `annunciator member on the housing, a cylindrical member slidably supported on the plug adjacent the extremity thereo-f, a collar secured to the-plug toltherear of the cylindrical member for forcing the cylindrical member into the jack todisengagethe resilient member from the groove in the plug when the annunciator member is moved in the direction of the housing, and resilient means for retracting the plug from the 'jack when the `resilient member is so disengaged from the groove at the extremity of the plug.

13. An indicating assembly for use in an electrical warning system including: a housing including a front wall having an aperture therein, an elongated annunciator member of generally rectangular configuration and cornposed of translucent material, Vsocket means mounted on the front'wall of Kthe housing, plug means mounted on the annunciator member to Abe inserted in the socket means in electrical contact therewith when `the annunciator member is supported on the housingand for supporting at least one electric lamp in the annunciator member in position to illuminate the annunciator member when the plug means isinserted in thesocket means, an elongated plug member mounted on the annunciator member and projecting from the rear face of the annunciator member to be inserted in the aperture in the front wall of the housing, a resilient jack mounted in the housing in alignment with the aperture therein to engage the plug and thereby releasably mount the annunciator member on the housing, and resilient means for releasing the elongated plug member from the resilient jack and de-energizing the electric lamp when `the annunciator `is moved in the direction of the housing and released.

No references cited. 

